[golang learning notes 2.1] sorting and searching in arrays in golang

Sort

Sorting is to put a set of data , The process of arranging data in order according to specified rules .
1. Bubble sort
Bubbling rule ： There will be two cycles ;arr.length-1 Secondary cycle ; for the first time 【 External circulation 】 A maximum number will appear in each cycle ; The second cycle 【 Internal circulation 】 Will exchange positions for numbers larger than yourself .

package main
import (
	"fmt"
)
func main() {
    
	// There is a random array 
	var arr [6]int = [...]int{
    103, 20, 35, 48, 15, 6}
	// cycles 
	var num int = len(arr) - 1
	// Define temporary variables that receive values to be exchanged 
	var t int = 0
	for i := 0; i < num; i++ {
    
		for j := 0; j < num-i; j++ {
    
			if arr[j] < arr[j+1] {
    
				t = arr[j+1]
				arr[j+1] = arr[j]
				arr[j] = t
			}
		}
	}
	// Print the results ：arr: [103 48 35 20 15 6]
	fmt.Printf("arr: %v\n", arr)
}

In order to find

package main
import (
	"fmt"
)
func main() {
    
	// There is a random array 
	var arr [6]int = [...]int{
    103, 20, 35, 48, 15, 6}
	var num int =103
	var index int=-1
	 for i := 0; i < len(arr); i++ {
    
		      if num ==arr[i]{
    
                    index=arr[i]
					break;
			  }
	 }
	 if index !=-1{
    
		fmt.Printf(" Tips : We found it  %v",index)
	 }else{
    
		fmt.Printf(" Tips : Not found  %v",index)
	 }
}

Two points search

package main

import (
	"fmt"
)

// Sort from small to large 
func paixu(arr *[6]int) [6]int {
    
	// cycles 
	var num int = len(arr) - 1
	// Define temporary variables that receive values to be exchanged 
	var t int = 0
	for i := 0; i < num; i++ {
    
		for j := 0; j < num-i; j++ {
    
			if arr[j] > arr[j+1] {
    
				t = arr[j+1]
				arr[j+1] = arr[j]
				arr[j] = t
			}
		}
	}
	var arr2 = arr
	return *arr2
}

// Two points search 
// Binary search is to find an ordered array or slice ; If there is no continuation, it will not be established 
func BinaryFind(arr *[6]int, leftIndex int, rightIndex int, findValue int) {
    
	// If the left subscript is greater than the right subscript ; The representative has looked for all , And I can't find 
	if leftIndex > rightIndex {
    
		fmt.Printf(" No data found ")
		return
	}
	// Find the middle subscript 
	middle := (leftIndex + rightIndex) / 2
	// If the value in the array is greater than the value to be found , Then continue to look to the left ; On the contrary, look to the right , If equal, then the middle is what we want to find , You can find it in one search 
	if (*arr)[middle] > findValue {
    
		BinaryFind(arr, leftIndex, middle-1, findValue)
	} else if (*arr)[middle] < findValue {
    
		BinaryFind(arr, middle+1, rightIndex, findValue)
	} else {
    
		fmt.Printf(" eureka %v", findValue)
		return
	}
}
func main() {
    
	// There is a random array 
	var arr [6]int = [...]int{
    103, 20, 35, 48, 15, 6}
	paixu(&arr)
    //arr: [6 15 20 35 48 103]; Because it was addressed , therefore arr It will change too. 
	fmt.Printf("arr: %v\n", arr)
	// Two points search 【len(arr-1)  It's because the subscript of the array is 0 At the beginning 】
	BinaryFind(&arr, 0, len(arr)-1, 20)
}

Definition and use of two-dimensional array

package main

import (
	"fmt"
)

func main() {
    
	// First define in assignment 
	var arr [2][3]int
	arr[0][2] = 1
	arr[1][1] = 2
	arr[1][2] = 3
	// Unassigned values go to default 
	// Print the results arr: [[0 0 1] [0 2 3]]
	fmt.Printf("arr: %v\n", arr)
	// Traversal mode 1 
	for i := 0; i < len(arr); i++ {
    
		for j := 0; j < len(arr[i]); j++ {
    
			fmt.Print(arr[i][j], "")
		}
		fmt.Println()
	}
	// Direct initialization 
	var arr2 [2][3]int = [2][3]int{
    {
    1, 2}, {
    1, 2, 3}}
	// Print the results arr2: [[1 2 0] [1 2 3]]
	fmt.Printf("arr2: %v\n", arr2)
	// Traversal mode 2 
	for _, v := range arr2 {
    
		for _,vv:= range v {
    
				fmt.Printf("vv: %v\n", vv)
		}
	}
}